This is my all time FAVORITE lens for animals. The 70-200, while being an excellent lens, just didn't have the reach that I wanted/needed for animal shots. THis lens does. It's crisp and sharp -- w/out fail. And the color in extraordinary.

I went through 2 copies of this lens and thehy were both missing that little something called sharpness. I sent both copies back to where I bought them from (2 different camera places) and got a 16-35. I haven't looked back since.

Like everyone else, I debated and debated between this and the 17-40 f/4. In all actuality, the 17-40 won out, but I was sorely disappointed in the results of the lens. It wasn't sharp enough. I thought it was the lens so I sent it back and got a replacement. But the results were the same. It was just missing that *oomph*

So, I sent the 2nd 17-40 back and broke down to spend the extra and get the 16-35 and OH MAN could I tell a difference immediately in the sharpness/crispness factors of the images. ANd there was a world of difference in the colors.